In order to examine the sensitivity of the USFT system to changing PpIX concentration in a homogeneous medium, the system was tested using homogeneous liquid phantoms containing Intralipid (20%, Fresenius-Kabi, Bad Homburg, Germany), 5% Tween20 (P1379, Sigma-Aldrich), porcine whole blood (7204901, Lampire Biological inc.), and [0,0.025,0.05,0.1,0.2,0.4,0.8] PpIX. Blood and Intralipid concentrations were varied to generate a sampling cross using: values for (blood%, Intralipid%) were (1%, 0.5%) (1%, 1%) (1%, 1.5%) (0.5%, 1%) (1.5%, 1%). Each phantom was stirred continuously until imaging.29,47 Three images were obtained for each combination of blood, Intralipid, and PpIX concentration, resulting in 15 measurements at each PpIX concentration, with three measurements for each of the five blood/Intralipid values. Reconstruction was performed in two stages. First, all phantoms were assumed to have equal optical properties based on values found in 34. Second, reconstructions were performed with phantom-specific optical properties, as measured by white light spectroscopy. Simulations were used to expand the range of optical properties, beyond those found in phantoms with blood (fully oxygenated), Intralipid. These simulations considered homogeneous phantoms with base optical properties of or and , with each optical property pair varied by factors of [0.5, 0.75, 1, 1.25, 1.5], and across 7 PpIX concentrations, for a total of 350 simulations. The simulated data, noise, was reconstructed using either the fixed base optical properties or the “measured” (known) optical properties with 5% noise. Normalized standard deviation (), reconstruction objective function error, , and reconstruction linearity with concentration were calculated in each case for all optical property sets and compared to determine the effect of known optical properties on reconstructed values.